Repair Cassandra with Reaper

Use the Reaper for Apache Cassandra® web interface to perform repairs.

Repairs are a critical anti-entropy operation in Cassandra. In the past, there have been many custom solutions to manage them outside of your main Cassandra installation. K8ssandra provides the Reaper web interface that eliminates the need for a custom solution. Just like K8ssandra makes Cassandra setup easy, Reaper makes configuration of repairs even easier.

Tools

  • Web Browser
  • values.yaml configuration, or use --set flags on the command line

Prerequisites

  1. Kubernetes cluster with the following elements deployed:
  2. DNS name configured for the Reaper web interface

Access the Reaper web interface

Reaper UI

With the prerequisites satisfied the Reaper web interface should be available at the following address:

http://REAPER_DOMAIN/webui

For example, to upgrade a previously installed k8ssandra that’s running locally, where the releaseName used on the prior helm install command was k8ssandra:

helm upgrade k8ssandra k8ssandra/k8ssandra --set reaper.ingress.enabled=true,reaper.ingress.host=localhost

After about five or more minutes, check that the pods are running. Example:

kubectl get pods

Output:

NAME                                                READY   STATUS      RESTARTS   AGE
k8ssandra-cass-operator-766849b497-klgwf            1/1     Running     0          7m33s
k8ssandra-dc1-default-sts-0                         2/2     Running     0          7m5s
k8ssandra-dc1-stargate-5c46975f66-pxl84             1/1     Running     0          7m32s
k8ssandra-grafana-679b4bbd74-wj769                  2/2     Running     0          7m32s
k8ssandra-kube-prometheus-operator-85695ffb-ft8f8   1/1     Running     0          7m32s
k8ssandra-reaper-655fc7dfc6-n9svw                   1/1     Running     0          4m52s
k8ssandra-reaper-operator-79fd5b4655-748rv          1/1     Running     0          7m33s
prometheus-k8ssandra-kube-prometheus-prometheus-0   2/2     Running     1          7m27s

What can I do in Reaper?

To access Reaper, navigate to http://localhost:8080/webui/.

Check the cluster’s health

In the Reaper UI, notice how the nodes are displayed inside the datacenter for the cluster.

Reaper cluster

The color of the nodes indicates the overall load the nodes are experiencing at the current moment.

See Check a cluster’s health.

Schedule a cluster repair

On the UI’s left sidebar, notice the Schedule option.

Reaper schedule

Click Schedules

Reaper add schedule

Click Add schedule and fill out the details when you are done click the final add schedule to apply the new repair job. A Cassandra best practice is to have one repair complete per week to prevent zombie data from coming back after a deletion.

Reaper add schedule part 2

Enter values for the keyspace, tables, owner, and other fields. Then click Add Schedule. The details for adding a schedule are similar to the details for the Repair form, except the “Clause” field is replaced with two fields:

  • “Start time”
  • “Interval in days”

After creating a scheduled repair, the page is updated with a list of Active and Paused repair schedules.

For additional information, see Schedule a cluster repair on the Reaper site.

Autoschedule repairs

When you enable the autoschedule feature, Reaper dynamically schedules repairs for all non-system keyspaces in a cluster. A cluster’s keyspaces are monitored and any modifications (additions or removals) are detected. When a new keyspace is created, a new repair schedule is created automatically for that keyspace. Conversely, when a keyspace is removed, the corresponding repair schedule is deleted.

To enable autoschedule in Reaper, set the property repair.reaper.autoschedule to true.

Run a cluster repair

On the repair job you just configured, click Run now.

Reaper run now

Notice the repair job kicking off.

Next steps

Explore other K8ssandra tasks.

See the Reaper Operator Helm Chart reference.



Last modified July 22, 2021: Fix links format (#999) (aac72ff)